Smaller components that comprise this entity, if any. If this entity is an atom, an
empty list is returned. TextBlock
is at the top of the Text hierarchy. TextBlock
contains Line
objects, which contains Elements.
Elements
are atoms. We may decide to add character-level objects in later versions.

For example, a client could draw bounding boxes for recognized text in different
colors for paragraphs, lines, words, and alphabets by repeatedly traversing down the
tree with this method.